cell.py

import tensorflow as tf
import numpy as np


class Cell(object):
	def __init__(self, state, h_activation,
		     input=None, first=False, prevCell=None):

		if first and input is not None:
			# Concatenates the vector of inputs with the vector of
                        # activations
			h_activation = tf.concat(0,
				[tf.transpose(input), h_activation])

		if first or prevCell is None:
			# Generates the gating matrices and biases
			print("Will initialize the first parameters...")
			self.wf, self.wi, self.wc, self.wo, \
			self.bf, self.bi, self.bc, self.bo = \
				self.initialize_parameters(
					state.get_shape().as_list()[0],
					h_activation.get_shape().as_list()[0],
					first)
		else:  # if not first and prevCell is not None:
			print("Will reuse awkeufahweufhkawe...")
			# TODO: Maybe create a class for these
			self.wf, self.wi, self.wc, self.wo, \
			self.bf, self.bi, self.bc, self.bo = \
				prevCell.wf, prevCell.wi, prevCell.wc, \
                                prevCell.wo, \
				prevCell.bf, prevCell.bi, prevCell.bc, prevCell.bo,

		f = tf.sigmoid(tf.matmul(self.wf, h_activation) + self.bf)
		i = tf.sigmoid(tf.matmul(self.wi, h_activation) + self.bi)
		c = tf.tanh(tf.matmul(self.wc, h_activation) + self.bc)
		o = tf.sigmoid(tf.matmul(self.wo, h_activation) + self.bo)

		self.state_next = tf.add(tf.mul(f, state), tf.mul(i, c))
		self.h_next = tf.mul(tf.tanh(self.state_next), o)
		return

	def initialize_parameters(self, n_s, n_h, first):
		""" Obviously, this function can be simplified.
		    It is this way only to aid debugging. """

		wf = tf.Variable(tf.truncated_normal([n_s, n_h], stddev=0.1))
		wi = tf.Variable(tf.truncated_normal([n_s, n_h], stddev=0.1))
		wc = tf.Variable(tf.truncated_normal([n_s, n_h], stddev=0.1))
		wo = tf.Variable(tf.truncated_normal([n_s, n_h], stddev=0.1))

		bf = tf.Variable(tf.constant(0.1, shape=[n_s, 1]))
		bi = tf.Variable(tf.constant(0.1, shape=[n_s, 1]))
		bc = tf.Variable(tf.constant(0.1, shape=[n_s, 1]))
		bo = tf.Variable(tf.constant(0.1, shape=[n_s, 1]))

		return wf, wi, wc, wo, bf, bi, bc, bo